This invention relates to improved rolls or stacks of thermoplastic bags and to thermoplastic bags with self-closing capability.
Rolls of polyethylene bags or bags of other plastic material are a standard commercial product. One well known example of such bags is a common-day plastic bag which is used for produce and bulk foods in grocery stores or supermarkets. These rolls consist generally of a tube of the plastic material, the two layers of which are sealed together at regular intervals along transverse lines, thus dividing the tube into separate pockets each of which will become an individual bag. Weakened areas, generally perforations, are provided adjacent the seals to enable the separation of each individual bag from the roll. Each individual bag thus incorporates one seal, to close one end, and a perforated opening at the other end. To use each bag, the shopper grasps and tugs the bag, tearing it from the reel along the line of perforation. Generally, the shopper closes the bag by twisting it shut and may use a separate fastening device called a twist tie if it also happens to be provided by the store.
Methods of manufacturing such rolls of bags are well known in the art. See, for example, U.S. Pat. Nos. 3,558,400 and 3,960,062.
Despite their wide commercial application, one major complaint regarding rolls of plastic bags is that they can be difficult to open. Often, the end of the bag defined by the perforations is difficult to open because the perforations can stick together during manufacture of the roll. Another major complaint regarding such plastic bags is that it is necessary to use a separate fastening device to close the bags. It is therefore desired to develop a roll or stack of bags which are more easily opened than the bags currently available and to develop bags which can be closed without the use of separate fastening devices.